Semantic analysis for explicit instantiation of class templates. We

still aren't instantiating the definitions of class template members,
and core issues 275 and 259 will both affect the checking that we do
for explicit instantiations (but are not yet implemented).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71613 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 135 insertions, 0 deletions

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index fc44217252..c80bb882f6 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -2141,6 +2141,141 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec, TagKind TK,
   return DeclPtrTy::make(Specialization);
 }
 
+Sema::DeclResult
+Sema::ActOnExplicitInstantiation(Scope *S, SourceLocation TemplateLoc,
+                                 unsigned TagSpec, 
+                                 SourceLocation KWLoc,
+                                 const CXXScopeSpec &SS,
+                                 TemplateTy TemplateD,
+                                 SourceLocation TemplateNameLoc,
+                                 SourceLocation LAngleLoc,
+                                 ASTTemplateArgsPtr TemplateArgsIn,
+                                 SourceLocation *TemplateArgLocs,
+                                 SourceLocation RAngleLoc,
+                                 AttributeList *Attr) {
+  // Find the class template we're specializing
+  TemplateName Name = TemplateD.getAsVal<TemplateName>();
+  ClassTemplateDecl *ClassTemplate 
+    = cast<ClassTemplateDecl>(Name.getAsTemplateDecl());
+
+  // Check that the specialization uses the same tag kind as the
+  // original template.
+  TagDecl::TagKind Kind;
+  switch (TagSpec) {
+  default: assert(0 && "Unknown tag type!");
+  case DeclSpec::TST_struct: Kind = TagDecl::TK_struct; break;
+  case DeclSpec::TST_union:  Kind = TagDecl::TK_union; break;
+  case DeclSpec::TST_class:  Kind = TagDecl::TK_class; break;
+  }
+  if (!isAcceptableTagRedeclaration(
+                              ClassTemplate->getTemplatedDecl()->getTagKind(),
+                                    Kind)) {
+    Diag(KWLoc, diag::err_use_with_wrong_tag) 
+      << ClassTemplate
+      << CodeModificationHint::CreateReplacement(KWLoc, 
+                            ClassTemplate->getTemplatedDecl()->getKindName());
+    Diag(ClassTemplate->getTemplatedDecl()->getLocation(), 
+         diag::note_previous_use);
+    Kind = ClassTemplate->getTemplatedDecl()->getTagKind();
+  }
+
+  // Translate the parser's template argument list in our AST format.
+  llvm::SmallVector<TemplateArgument, 16> TemplateArgs;
+  translateTemplateArguments(TemplateArgsIn, TemplateArgLocs, TemplateArgs);
+
+  // Check that the template argument list is well-formed for this
+  // template.
+  llvm::SmallVector<TemplateArgument, 16> ConvertedTemplateArgs;
+  if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc, LAngleLoc, 
+                                &TemplateArgs[0], TemplateArgs.size(),
+                                RAngleLoc, ConvertedTemplateArgs))
+    return true;
+
+  assert((ConvertedTemplateArgs.size() == 
+            ClassTemplate->getTemplateParameters()->size()) &&
+         "Converted template argument list is too short!");
+  
+  // Find the class template specialization declaration that
+  // corresponds to these arguments.
+  llvm::FoldingSetNodeID ID;
+  ClassTemplateSpecializationDecl::Profile(ID, &ConvertedTemplateArgs[0],
+                                           ConvertedTemplateArgs.size());
+  void *InsertPos = 0;
+  ClassTemplateSpecializationDecl *PrevDecl
+    = ClassTemplate->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
+
+  ClassTemplateSpecializationDecl *Specialization = 0;
+
+  if (PrevDecl) {
+    if (PrevDecl->getSpecializationKind() != TSK_Undeclared) {
+      // This particular specialization has already been declared or
+      // instantiated. We cannot explicitly instantiate it.
+      Diag(TemplateNameLoc, diag::err_explicit_instantiation_redef)
+        << Context.getTypeDeclType(PrevDecl)
+        << (int)PrevDecl->getSpecializationKind();
+      Diag(PrevDecl->getLocation(), diag::note_previous_instantiation)
+        << (int)PrevDecl->getSpecializationKind();
+      return DeclPtrTy::make(PrevDecl);
+    }
+
+    // Since the only prior class template specialization with these
+    // arguments was referenced but not declared, reuse that
+    // declaration node as our own, updating its source location to
+    // reflect our new declaration.
+    Specialization = PrevDecl;
+    Specialization->setLocation(TemplateNameLoc);
+    PrevDecl = 0;
+  } else {
+    // Create a new class template specialization declaration node for
+    // this explicit specialization.
+    Specialization
+      = ClassTemplateSpecializationDecl::Create(Context, 
+                                             ClassTemplate->getDeclContext(),
+                                                TemplateNameLoc,
+                                                ClassTemplate,
+                                                &ConvertedTemplateArgs[0],
+                                                ConvertedTemplateArgs.size(),
+                                                0);
+
+    ClassTemplate->getSpecializations().InsertNode(Specialization, 
+                                                   InsertPos);
+  }
+
+  // Build the fully-sugared type for this explicit instantiation as
+  // the user wrote in the explicit instantiation itself. This means
+  // that we'll pretty-print the type retrieved from the
+  // specialization's declaration the way that the user actually wrote
+  // the explicit instantiation, rather than formatting the name based
+  // on the "canonical" representation used to store the template
+  // arguments in the specialization.
+  QualType WrittenTy 
+    = Context.getTemplateSpecializationType(Name, 
+                                            &TemplateArgs[0],
+                                            TemplateArgs.size(),
+                                  Context.getTypeDeclType(Specialization));
+  Specialization->setTypeAsWritten(WrittenTy);
+  TemplateArgsIn.release();
+
+  // Add the explicit instantiation into its lexical context. However,
+  // since explicit instantiations are never found by name lookup, we
+  // just put it into the declaration context directly.
+  Specialization->setLexicalDeclContext(CurContext);
+  CurContext->addDecl(Context, Specialization);
+
+  // C++ [temp.explicit]p3:
+  //
+  //   A definition of a class template or class member template
+  //   shall be in scope at the point of the explicit instantiation of
+  //   the class template or class member template.
+  //
+  // This check comes when we actually try to perform the
+  // instantiation.
+  if (InstantiateClassTemplateSpecialization(Specialization, true))
+    return true;
+
+  return DeclPtrTy::make(Specialization);
+}
+
 Sema::TypeResult
 Sema::ActOnTypenameType(SourceLocation TypenameLoc, const CXXScopeSpec &SS,
                         const IdentifierInfo &II, SourceLocation IdLoc) {